Ultrasonic atomizer



y 16, 1968 CARL-GUNNAR D. ENGSTR'O'M ETAL 3,392,916

ULTRASONI C AT OMI ZER Filed Nov. 22, 1966 Fig.1

I NVENTOR 1 w m 1U R S Fm W vi M z ar e H DL TU a P W a f I: m m C3,392,916 ULTRASONIC ATOMIZER Carl-Gunnar Daniel Engstriim, Aluddsvagen3, Stockholm, Sweden, and Paul Herzog, Nybodagatan 7, Solna, SwedenFiled Nov. 22, 1966, Ser. No. 596,175 Claims priority, applicationSweden, Dec. 8, 1965, 15,903/ 65 4 Claims. (Cl. 239102) ABSTRACT OF THEDISCLOSURE An ultrasonic atomizer to form aerosols having a chamberthrough which a current of gas flows and in which an ultrasonic vibratoris located. The liquid to be atomized is fed to the vibrating face ofthe vibrator.

The present invention relates to an ultrasonic atomizer for atomizingliquids and forming an aerosol.

The atomization of liquids by means of an ultrasonic vibrator isassociated with several problems. Among the most important of these arethe damping effect when supplying excess of liquid to the vibratingbody, the difiiculty of controlling the amount of liquid atomized perunit of time and the problem of insulating the current supply lead inthose cases, where the vibrating body is wholly or partly surrounded byliquid. These problems have not been acceptably solved in knownultrasonic atomizers, in view of which the atomizers have not gained adesired broad application.

The present invention aims at solving said problems, whereby anultrasonic atomizer is obtained which in view of its reliability andsimple design has a many-facetted use.

The ultrasonic atomizer according to the invention for atomizing liquidsand forming an aerosol comprises an atomizing chamber having a gas inletand a gas outlet, and a vibrating body arranged in the atomizing chamberand having a vibrating surface, which is adapted to receive liquid foratomization from liquid supply means, the vibrating surface beingarranged inclined, preferably essentially vertically, and the liquidsupply means being so arranged relative to the vibrating surface, thatthe liquid in the supply means is in continuous liquid contact with theliquid atomized at the vibrating surface. The liquid supply means maycomprise a liquid supply tube opening adjacent to the vibrating surfaceand the mouth of which is bevelled so as to be essentially parallel withthe vibration surface and possible engages same with its outmost tip,the liquid supply tube suitably being elastically suspended.

In a particular embodiment of the invention the liquid supply meanscomprises a device, for instance a displacement pump, giving acontrollable constant flow of liquid to the vibrating surface.

The invention will now be described by an example with reference to theappended drawing, wherein FIG. 1 shows, partly in section, an embodimentof the ultrasonic atomizer according to the invention, and FIG. 2 shows,on an enlarged scale, a detail of the ultrasonic atomizer of FIG. 1.

The ultrasonic atomizer shown in FIG. 1 comprises a container, generallydesignated 1, having side walls 3, one end wall 5 integral therewith andone removable end wall 7 attached to the side walls 3 by means of screws9. In order to obtain sealing a gasket 11 is clamped between theremovable end wall 7 and the side walls 3 of the container. Thecontainer has a gas inlet 13 arranged in the end wall 5 and a gas outlet15 centrally positioned in the removable end wall. 7. In the lower partof the container 1 a drain tube 17 having a shut-01f cock 19 isprovided.

nited States Patent 0 3,392,916 Patented July 16, 1968 An ultrasonicvibrator 21 is arranged in the removable end wall 7 and extends inwardlyinto the container 1 and ends in a vertical vibrating surface 23, thevibrator being supplied with high frequency current through a coaxialcable 25.

The liquid to be atomized is stored in a bottle 27, which is suspendedin a bracket 29 upside down. The bottle can be an ordinary hospital dropflask, used for instance when giving blood transfusions. The bottle 27is sealed by means of a plug 30 penetrated by a liquid discharge tube 31and an air inlet tube 33 extending above the free surface of the liquidin the bottle. A flexible hose 35 provided with a hose clamp 37 isconnected to the tube 31. The hose 35 leads to the inlet of a pump P,the outlet of which is connected to a liquid supply tube 39. This tube39 is received in an aperture in the upper side of the container 1, thetube being arranged in a plug 41, for instance made of rubber. The mouth43 of the liquid supply tube 39 is bevelled so as to be adapted to thevibrating surface 23, adjacent to which it opens. The inclination oz ofthe tube 39 relative to the vertical plane coinciding with the vibratingsurface 23 should be small as possible and suitably less than 30.

FIG. 2 shows, on an enlarged scale, a section through the pump P. Thepump is a so-called displacement pump and consists of a pump housing 51having an inlet 53 and an outlet 55, and pump elements 57, 59, havingopposite rotational directions.

Briefly, the function of the apparatus is the following:

A continuous flow of carrier gas is supplied to the container 1 throughthe gas inlet 13, the gas outlet 15 being connected to a device to whichan aerosol is to be supplied, for instance a respirator, an oil burneror the like. When the flow of carrier gas has been adjusted to asuitable value the ultrasonic vibrator 21 and the pump P is startedafter opening the hose clamp 37. The pump speed is adjusted to provide asuitable liquid flow and a predetermined amount of liquid per unit oftime is now supplied to the vibrating surface 23, where it issuccessively atomized when leaving the mouth 43 of the tube 39, and theatomized liquid is then carried by the carrier gas out through theoutlet 15.

By using the arrangement suggested several advantages are gained. Bymeans of the displacement pump an ac curate supply of liquid isprovided. In view of the vertical arrangement of the vibrating surfacethere is no risk of damping the vibrations of the vibrating body whensupplying excess of liquid, as non-atomized liquid immediately flows offfrom the vibrating surface, the efficiency of the ultrasonic vibratorthus being unchanged. The liquid flown off from the vibrating surfacecan be discharged from the container 1 through the tube 17 at regularintervals by opening the cock 19. Thanks to the fact that the ultrasonicvibrator does not come into contact with the liquid, except, of course,at the vibrating surface, the insulating problem at the point ofconnection of the current supply cable is essentially facilitated.

The present invention thus provides an ultrasonic atomizer which, inview of its ability to generate an aerosol having a well definedcomposition, has a multifarious use. It may for instance be used inrespirators for the supply of moisture, anaesthetica, etc., in flamespectrometry for the generation of an aerosol containing the element tobe analyzed for the supply of fuels in diesel engines, oil burners, jetmotors, etc.

The invention is, of course, not limited to the embodiment shown in thedrawing. Thus, the pump P may be removed, the supply of liquid beingcontrolled by changing the height of the flask 27 or contracting thehose clamp 37. The pump P can be of any type but is preferably adisplacement pump giving a continuous flow of liquid. The pump can besupplied with liquid from a iquid container of any design and can besupplied with iquid under pressure or operate with self-suction. Nor sit necessary that the vibrating surface is positioned Iertically. Theimportant thing is that said surface has [11 inclination which gives anefiicient runoff from the Iibrating body so as to prevent damping of thevibrations )f said body. Generally, the angle between the vibrating:urface and the vertical should be less than 45".

What is claimed is:

1. Ultrasonic atomizer for atomizing liquids and formng an aerosol,comprising an atomizing chamber having t gas inlet and a gas outlet, anda vibrating body arranged n the atomizing chamber and having a vibratingsurace, which is adapted to receive liquid for atomization rom liquidsupply means, in which the vibrating surface 5 arranged inclined,preferably essentially vertically, and he liquid supply means are soarranged relative to the 'ibrating surface, that the liquid in thesupply means s in continuous liquid contact with the liquid atomized .tthe vibrating surface.

2. Ultrasonic atomizer according to claim 1, in which he liquid supplymeans comprises a liquid supply tube 4 opening adjacent to the vibratingsurface and the mouth of which is bevelled so as to be essentiallyparallel with the vibration surface and possibly engages same with itsoutmost tip, the liquid supply tube suitably being elasticallysuspended.

3. Ultrasonic atomizer according to claim 1 or 2, in which the liquidsupply means comprises a device, for instance a displacement pump,giving a controllable constant flow of liquid to the vibrating surface.

4. Ultrasonic atomizer according to any of the preceding claims, inwhich a liquid drain means is positioned in the lower part of theatomizing chamber.

References Cited UNITED STATES PATENTS 1,939,302 12/1933 Heaney 239-1023,038,532 6/1962 Eisenkraft 1594 3,200,873 8/1965 Young et al. 158-773,214,101 10/1965 Perron 239-102 EVERETT W. KIRBY, Primary Examiner.

